The present invention is concerned with a tabulating apparatus, particularly a tabulator apparatus which permits the release of the tabulating key prior to arriving at the tabulator stop. The typewriter has exchangeable type carriers which require carriage steps of different length.
The German Auslegschrift 1,815,871 and the corresponding U.S. Pat. No. 3,540,565 disclose a tabulating apparatus which cooperates with a rack bar escapement mechanism shiftable between conditions in which carriage steps of different length are obtained. The tabulator apparatus has a tab carrier bar on which tabs are mounted whose number and spacing corresponds to the smallest distance between two teeth of the escapement mechanism. The tabs are arranged in a row at different distances so that, after consideration of tolerances of the escapement pawl and the toothed escapement member, each tab is associated with a recess between two teeth of the escapement rack bar assuring a proper engagement of the escapement pawl. The tabulating apparatus of the prior art has the disadvantage that the escapement pawl, which is released by the differently spaced tabs in the respective stop positions has different time periods and distances available for engaging the escapement rack bar. Since the escapement pawl, after release by the tabulating arrangement, freely falls into the respective recess of the escapement rack bar, wrong engagements may occur so that the escapement pawl stops the carriage in a wrong column.
The apparatus according to the prior art requires an extremely great precision for the entire tabulating apparatus and for the escapement mechanism. Furthermore, all parts have to be very carefully adjusted during assembly, which increases the manufacturing costs. Another disadvantage of the apparatus of the prior art resides in that it can be used only for different types requiring only little different basic steps, so that only a limited number of fonts of types can be used with the apparatus.